The present invention relates to a color video display apparatus for vehicles which is mounted in the vehicle compartment to provide various displays.
For the color balance of a color CRT, it has been the practice in the past to adjust the intensity ratios of the emitted R, G and B colors and thereby to set the white color to a reference value. Then, taking the sum of the emitted R, G and B colors forming the reference color as "1", the intensities of the emitted colors have been varied within this range to produce any desired colors.
Such reference white color has differed depending on the preference of people, the kind of the outdoor light during the observation etc., and therefore the reference white color having a color temperature of 6,500.degree. K. has been used for a long time in Europe and America, while in Japan the reference white color has been specified as a color temperature of 8,300.degree. to 10,000.degree. K.
Considering now a color CRT for use in a vehicle, there are instances where the eyes of an observer are adapted to the indirect rays of the sun in the daytime and where the eyes are adapted for the scotopic vision in the nighttime. Therefore, if the display on a color CRT having the white set to a color temperature of 8,300.degree. K. as mentioned previously is observed, there is an inconvenience that the blue is emphasized considerably and the red is caused to appear excessively dark. This will be described with reference to the spectral luminous efficiency curves of man shown in FIG. 2. During the light hours of day the human eyes have a relative luminous efficiency under the conditions of photopic vision in the Figure and the color balance of the ordinary color CRT is effected in accordance with such human luminous efficiency. However, during the hours from twilight to night the relative luminous efficiency of the human eyes is shifted toward the shorter wavelengths as shown under the conditions of scotopic vision in the FIG. 2. As a result, the color balance of the color CRT effected as mentioned previously becomes such that the blue and bluish green colors are excessively intensified and the yellow, orange and red colors are caused to appear extremely dark due to a change in the luminous efficiency of the human eyes.